Which fitting is used to connect two pipes at a 90-degree angle?

The fitting used to connect two pipes at a 90-degree angle is known as an elbow. Elbows are specifically designed to change the direction of the piping system, allowing for fluid flow to navigate turns in a piping network. This fitting is essential in various plumbing and piping applications, such as in HVAC systems, drainage, and water supply lines, where directional changes are necessary for proper routing and installation.

In contrast, couplings are fittings used to join two straight sections of pipe together in a linear fashion, without any angle change. Reducers are fittings designed to transition between different pipe sizes to accommodate changes in flow requirements while maintaining efficiency. Tees are used to create a branch in a piping system, connecting another section perpendicular to the main line, but they do not focus on connecting two pipes strictly at a right angle. Thus, the elbow fitting fulfills the requirement of connecting two pipes at a 90-degree angle effectively.